Self-raising flour is a mixture of flour and food additives. Food additives are the key to self-raising flour. This food additive belongs to leavening agent, also known as leavening agent. The leavening agent can be divided into alkaline leavening agent and compound leavening agent. Using single alkaline leavening agent, the taste of the product is poor, so people often use compound leavening agent. The compound leavening agent is used in self-raising flour. The compound leavening agent consists of an alkali agent and an acid agent. In the process of cooking, baking or frying, the alkaline agent and the acid agent undergo a neutralization reaction, releasing carbon dioxide gas, gradually increasing the volume of dough or egg paste, and finally making steamed bread, cakes or fried dough sticks. There is no residual alkaline substance in the product, which improves the product quality. The key of compound leavening agent is the choice of acid agent. The experiment shows that the effect of leavening agent and the quality of products can be fully improved if proper acid agent is selected.

Low-gluten flour refers to flour with water content of 13.8% and crude protein content less than 8.5%, which is usually used in cakes, biscuits, cakes and pastries. Sponge cake is made of low-gluten flour. Because low-gluten flour has no strength, the cakes made are particularly soft, loose and flat.